STS-75 press kit

Edited by Richard W. Orloff, 01/2001/Page 15
TETHERED SATELLITE SYSTEM REFLIGHT (TSS-1R)
NASA and ASI long have planned the TSS reflight but a formal commitment awaited U.S. congressional
approval for NASA to spend funds on the project. TSS originally was flown on the Space Shuttle STS-46
mission launched in July 1992. TSS deployment was curtailed when mechanical interference in the
deployer reel assembly prevented full deployment of the satellite. The TSS reflight will focus on science
objectives not accomplished on the STS-46 mission.
The TSS flight will be a scientific adventure aimed at understanding the possibilities for putting tether
technology to work in space for many uses. TSS-1R will take advantage of the knowledge gained about
tether dynamics during the first TSS mission. This mission will gather more crucial information needed to
test theories for a variety of future tether applications.
For example, by reversing the direction of the current in the tether, the force caused by its interaction with
Earth's magnetic field could put an object in motion, serving to boost a spacecraft's orbit without using
precious fuel. Also, a satellite could be moved up and down in orbit by releasing a tethered body from a
primary spacecraft to position it into a desired location. Deploying a tether downwards towards Earth could
place movable science platforms in hard-to-study atmospheric zones, such as the ozone region over the
South Pole.
Tethers also may be used as antennas to transmit extremely low frequency signals to Earth. Such low
frequency waves can penetrate land and sea water providing for communications not possible with
standard radio. Tethers could place instrumented experimental aircraft models in the region 60 to 90 miles
(100 to 150 kilometers) above Earth to gain a more accurate evaluation than is possible in wind tunnels,
which only partially simulate flight conditions. It may one day be possible to create artificial gravity for
long-duration missions, such as the first human trip to Mars, by using tethered systems.
TSS-1R experiments support seven mission objectives:
1. Determine the amount of electrical current collected and voltage produced by the Tethered Satellite-
Shuttle system as it interacts with Earth's ionospheric environment of charged gas (plasma) and its
magnetic and electric fields.
2. Understand how a tethered satellite makes contact with the ionospheric plasma and how an electrical
current is extracted.
3. Demonstrate electrical power generation, as a product of current and voltage, to determine how such a
system could be used as a space-based power source.
4. Verify tether control and dynamics from short (1.2 mile/2 kilometer) to long (12.8 mile/20.7
kilometer) deployment ranges.
5. Demonstrate how neutral gas affects the satellite's plasma sheath and current collection, possibly
enhancing tether-produced current.
6. Determine how electrical current is conducted through the near-Earth plasma by measuring waves
broadcast as the tethered satellite passes over a series of ground-based receiving stations, as well as
how the tether acts as a low- frequency-band antenna.
7. Learn to control tether motion by collecting data about how current flow produces force.